Ignition system



E. M. CLAYTOR ET AL 2,317,583

IGNITION SYSTEM Filed Nov. 7, 1940 ATTORNEY a grounded contact 33.

Patented Apr, 27, 1943 IGNITION SYSTEM Edward M. Claytor and William J. Rady, Anderson, Ind., assignors to General Motors Corporation, Detroit; Mich., a corporation of Delaware Application November 7, 1940, Serial No. 364,702

4 Claims.

This invention relates to ignition systems for internal combustion engines and more particularly to the type of system in which a current source such as a storage battery is used to supply the ignition current. In such system a pcriodic circuit make and break device called the ignition timer is used to connect the current source with an ignition coil having a primary in series with the-timer and current source and having its secondary connected with an ignition distributor. In such system a manually operated switch is used for controlling the flow of current from the current source with the ignition apparatus. If the operator should fail to open this switch and if the engine should stop with the ignition timer contacts closed, the battery would The drawing is a wiring diagram embodying the present invention.

Referring to the drawing, ignition apparatus comprises an ignition coil l having a primary coil II and a secondary winding l2 connected respectively with ignition timer I 3 and distributor l4. The timer includes an engine operated cam l5 for engaging the rubbing block l6 of the circuit breaker lever I! connected by a leaf spring I8 with a terminal l9 connected with the primary coil II. The lever I! carries a contact for engaging a grounded contact 2|. The ignition coil receives its current from a battery 22 connected with the coil through a manually operated switch 23 and through the contacts 24-and 25 of a relay switch 26 having a magnet coil 21. Ai'ter switch 23 is closed, magnet coil 21 is energized by c1osing a push button switch 28 connecting switch j 23 with coil 21. Coil 21 is connected with circuits 230i a thermal switch 30 having a bimetallic blade 3| carrying-a contact 32 normally'engaging The blade 3l-is heated by a heater resistance 34 connected between coil lll'and contact 25 of relay26.

-To turn on the ignition, the operator closes the mainignition switch 23 which may be locked 7 current source with the primary winding and open by a key) and then closes the push button switch 28 whereupon relay magnet coil 21 will be connected with the battery and contacts 24 and 25 will be closed. The operator may then release the switch 28 as contacts 24 and 25 will remain closed so long as relay coil 27 is energized. Relay coil 21 will remain energized so long as contacts 32 and 33 of thermostat switch 30 remain closed, During the normal operations of the ignition apparatus the circuit through the heater resistance 34 as well as the primary coil H is closed only intermittently. Therefore, the heating efiect 01' a heater resistance 34 is limited to such an amount that the thermal switch 30 will not open while the engine is running. If the engine should stop with timer contacts 20, 2| engaged and if the operator should fail to open switch 23, the continuous current flow through heater resistance 34 will be such to heat the bimetallic plate suinciently to efiect separation of contact 32 from contact 33. Then the relay coil 21 will be disconnected from the battery and contacts 24 and 25 will open and the circuit from the battery 22 to the ignition coil will be interrupted.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. An ignition circuit comprising a current source, a timer, an ignition coil primary winding, a relay having a magnet coil and a pair of normally open contacts which, when closed, make a connection between the current source and the magnet coil and between the current source and the primary winding and timer, a thermal switch for normally making a connection between the current source and relay magnet coil, said thermal switch having provisions responsive to continuous current flow to the primary winding for causing the thermal switch to interrupt said connection. made by it, but not responsive to intermittent current flow while the engine is running, a manually operated switch in parallel with the relay contacts and means independent of the thermal switch for rendering the relay magnet coil ineffective to hold the relay contacts closed.

2. An ignition circuit comprising a current source, a timer, an ignition coil primary winding, a manually operated switch for connecting the timer, said switch having spring means biasing it to open position, arelay having a magnet coil parallelling the primary winding and timer and a pair of normally open contacts parallelling said manually operated switch, a thermal switch for normally making a connection between the current source and the relay magnet coil, said thermal switch having provisions responsive to continuous current flow to the primary winding for causing the interruption of the connection made by the thermal switch, but not responsive to intermittent current flow while the engine is running, and a switch for disconnecting .the current source from the relay magnet coil independently of the thermal switch.

3. An ignition circuit comprising a current source, a timer, an ignition coil primary winding, a manually operated switch for connecting the current source with the primary winding and timer, a relay having a magnet coil parallelling the primary winding and timer and a pair of normally open contacts parallelling the manually operated switch, and a thermal switch comprising a bimetal blade and a pair of normally closed contacts for making a connection between the current source and relay magnet coil, one of the contacts being actuated by the blade, and a blade heater in the circuit of the primary winding and timer so related to the blade that the blade will separate the contacts of the thermal switch in response to continuous current flow through the primary winding, but not in response to intermittent current flow while the engine is running,

and means independent of the thermal switch for rendering the relay magnet coil ineffective to hold the'relay contacts closed.

4. An ignition circuit comprising a current source, a timer, an ignition coil primary winding, a manually operated switch for connecting the current source with the primary winding and timer, a relay having normally open contacts parallelling the manually operated switch and having a magnet coil for eflecting the closing of said normally open contacts in order that, when the magnet coil is energized, a connection between. the current source and primary winding and timer will be made independently of the manually operated switch, and a series circuit including the current source, said manually operated switch, said relay magnet coil, 9. second manually operated switch and a thermal switch, said thermal switch having provisions responsive to continuous current flow to the primary winding for causing the interruption of the connection normally made by the thermal switch, but not responsive to intermittent current flow while the engine is running, said second manually operated switch being operable to open the said series circuit whereby the relay magnet coil is rendered inefiective, independently of the thermal switch, to hold the relay contacts closed. 

